This invention relates to trench shoring assemblies and, in particular, to a type of trench shoring assembly known as a trench box which is protected from abrasion at its lower extremities by an abrasion protective device.
Trench boxes are a type of trench shoring assembly used in excavation work when pipe is being laid. Trench boxes basically consist of two side walls spaced apart a fixed distance from each other by a plurality of spreader devices affixed to and perpendicular to each side wall. The assembled trench box is positioned in an excavated hole or trench and pipe or conduit is laid within the trench box, and after each length of pipe is laid the trench box is moved along the trench for laying the next length of pipe. The side walls of the trench box keep the excavation area free from earth which may fall or cave into the excavated hole or trench before or during the laying of the pipe.
When a trench box is positioned within an excavated hole or trench it is desirable that the lower ends of the trench box side walls dig into the bottom of the hole or trench to prevent the lateral flow of water or mud into the pipe laying area. To provide this feature the side walls of the trench box must be wedged into the earth. Prior trench boxes have a triangularly shaped pointed lower extremity in order to wedge the side walls into the earth; however, the wedging action of the side wall damages this lower extremity.
In accordance with the subject invention there is provided a trench shoring assembly of the type including a pair of interconnected spaced wall means having a predetermined thickness and a tapered bottom portion defining a triangularly shaped pointed lower extremity extending between the ends thereof and and abrasion protection means disposed at the pointed lower extremity and extending between the ends of the bottom portion for protecting the bottom of the wall means against abrasion. The abrasion protection means comprises a metallic bar.